[R6RS] `put-datum' constraints

[Michael Sperber]

Should we constrain the output of `put-datum' in any way?  Possible
axes:

- character set used / escapes in character, string, symbol literals
- number representation
- abbreviations for `quote' & friends
- whitespace
- square brackets

(I'm probably forgetting some.)

My personal preference would be to constrain the character set to
ASCII, and leave the rest up to the implementation.

Also, now that we require delimiters after character and boolean
literals, should we require `put-datum' to output delimiters after
characters and booleans?  This would (I hope) ensure that the output
of subsequent calls to `put-datum' can be read back with subsequent
calls to `get-datum'.

-- 
Cheers =8-} Mike
Friede, Völkerverständigung und überhaupt blabla